Situation: Measuring 75 ohm signals (off air TV stations for example) from a antenna into a SLM that was designed for 75 ohm vs doing the same into a spectrum analyzer that was designed for 50 ohms. Devices; Tektronix RFM151 Signal Scout SLM & Instek GSP-827 Spectrum Analyzer Questions; 1. That 75 to 50 ohm 'mismatch' equates to a 1.5:1 mismatch, correct? 2. If so, is that really a big deal if all I was comparing was signal levels and how the two devices related with the same signal level? A 1.5:1 SWR has always been aceptable as far as I know, so why would it be a issue here? The reason for the question, the manufacture of the SA is claiming this is what accounts for the drop in sensistivity between the two devices. The SLM shows a signal 8-10db above the noise floor, while the Instek barely regesters the signal at all. Input?